Current concepts on the pathophysiology of toxemia of pregnancy have been derived by correlating clinical observations with experiments using animals with bicornuate uteri and the reproductive tract in these animals is quite different from that of the human female. In view of these differences, it seemed to us that a better experimental model could be developed by the use of subhuman primates. Their reproductive physiology is remarkably similar to that of the human, and this certainly should make the findings more meaningful. In an effort to clarify the pathophysiology of toxemia of pregnancy, the baboon (Papio anubis) was selected as the experimental animal and a pilot study has been performed. Following partial occlusion of the uterine arteries and transection of the ovarian arteries, it was found that those animals which became pregnant developed hypertension and proteinuria. In addition, immunofluorescent, light and electron microscopy studies showed changes consistent with the renal changes in the human female suffering from toxemia of pregnancy. This is the first time that a successful primate model has ever been developed. However, the study took 8 years to complete because of the relative infertility of the animals following transection of the ovarian vessels, and the investigators now fell confident that an even better model can be developed using animals which are already pregnant. This would have the obvious advantage of expediting the entire investigative program with regard to pathogenesis and treatment methods.